Privacy issue in social network usually involves system breaches or exploitation of a user's private information. However, a privacy violation can occur during normal social interactions when sensitive data is relayed to a person that is outside of the originally-targeted group. One example is after a user shares his personal information (e.g., a picture, phone number) to a close circle of friends, a member of that group may accidentally or intentionally expose that sensitive information to the users outside of the group.